This page explains how Kai Zhang (USATT# 86637)'s rating went from 2644 to 2643 at the Westchester September 2018 Open held on 29 Sep 2018 - 30 Sep 2018. The links below take you to pages that describe various aspects of the rating processor.

The rating processor goes through 4 passes in order. The links take you to pages that provide detailed explanations of the calculations during each of the 4 passes.